5a-Androstane-3a,17b-diol activates pathway that resembles the epidermal growth factor responsive pathways in stimulating human prostate cancer LNCaP cell proliferation RA Zimmerman 1 , I Dozmorov 2 , EH Nunlist 1 , Y Tang 2 , X Li 1 , R Cowan 1 , M Centola 2 , MB Frank 2 , DJ Culkin 1 & H-K Lin 1 * 1 Department of Urology, University of Oklahoma Health Sciences Center, Oklahoma City, Oklahoma, USA; and 2 Arthritis and Immunology Program, Oklahoma Medical Research Foundation, Oklahoma City, Oklahoma, USA 5a-Androstane-3a,17b-diol (3a-diol) is considered to have no androgenic effects in androgen target organs unless it is oxidized to 5a-dihydrotestosterone (5a-DHT). We used microarray and bioinformatics to identify and compare 3a-diol and 5a- DHT responsive gene in human prostate LNCaP cells. Through a procedure called ‘hypervariable determination’, a similar set of 30 responsive genes involving signal transduction, transcription regulation, and cell proliferation were selected in 5a-DHT-, 3a-diol-, and epidermal growth factor (EGF)-treated samples. F-means cluster and networking procedures showed that the responsive pattern of these genes was more closely related between 3a-diol and EGF than between 5a-DHT and 3a-diol treatments. We conclude that 3a-diol is capable of stimulating prostate cell proliferation by eliciting EGF-like pathway in conjunction with androgen receptor pathway. Prostate Cancer and Prostatic Diseases (2004) 7, 364–374. doi:10.1038/sj.pcan.4500761 Published online 28 September 2004 Keywords: 5a-dihydrotestosterone; 5a-androstane-3a; 17b-diol; androgen receptor; epidermal growth factor; microarray analysis Introduction Androgens are responsible for development, growth, differentiation, and function of the prostate. 5a-Dihy- drotestosterone (5a-DHT), the most potent androgen in the prostate with high affinity toward the androgen receptor (AR; K d ¼ 10 10 M), 1 modulates androgen re- sponsive gene (ARG) expression, 2,3 and has been implicated in the development of prostatic diseases including benign prostatic hyperplasia (BPH) and prostate cancer (PCa). 4 Within the prostate, 5a-DHT can be reduced to weaker androgens, including 5a- androstane-3a,17b-diol (3a-diol) and 5a-androstane- 3b,17b-diol (3b-diol), through the action of 3a-hydro- xysteroid dehydrogenase (3a-HSD) and 3b-HSD, respec- tively. Of these two pathways, prostatic 3a-HSDs play dominant roles in 5a-DHT reduction. 5,6 3a-Diol has a low binding affinity toward the AR with K d ¼ 10 6 M, 7 and it is believed that 3a-diol must first be oxidized to 5a-DHT by 3a-HSD, 8 retinol dehydrogenase (RoDH), 9 11-cis-retinol dehydrogenase (RDH5), 10 or mitochondrial L-3-hydroxyacyl coenzyme A dehydro- genase (ERAB, 17b-HSD type 10) 11 before exerting its androgenic effects. However, increasing evidence sug- gests that 3a-diol may be an important androgen in the induction of prostatic hyperplasia through yet undefined pathways, 12 including cAMP, 13 in a castrated dog model, 8,14,15 in virilizing rat urogenital tract, 16 and in Received 12 May 2003; revised 4 December 2004; accepted 7 June 2004; published online 28 September 2004 *Correspondence: H-K Lin, Department of Urology, University of Oklahoma Health Sciences Center, 920 Stanton L Young Blvd, WP3150, Oklahoma City, OK 73104, USA. E-mail: hk-lin@ouhsc.edu Prostate Cancer and Prostatic Diseases (2004) 7, 364–374 & 2004 Nature Publishing Group All rights reserved 1365-7852/04 $30.00 www.nature.com/pcan